Suppose you met an alien with no concept of humor. How would you explain to him why we find certain things to be funny? You can say that it’s a reaction to the absurd or unexpected, but I don’t think this is true in every case, and moreover, not all absurd things are funny. Can all jokes be placed into categories? Would it be possible to program a computer to distinguish a statement which is funny from one that isn’t?
Basically, what I’m getting at is “What makes things funny?”
Well I hope for your sake that this Alien culture doesn’t think cruelty is funny… 
I’ve seen people running over dogs on the sidewalk for fun… I’ve seen people laughing at cruel behaviour. So I don’t think you need an alien to figure out that humour is in the eye of the beholder.
Funny can be categorized from what you’ve said: Sarcasm, absurdity, humiliation, unexpected, ridicularization, comic, stereotyping… must be a long list
I was just reading about how humor has been very under-studied by the academic community.
So if no one can answer your question satisfactorily, be forgiving.
What determines if something is funny?
George Bush said it.
I think this says it all.
Didn’t Niven say that the reason in his works that the reason the puppeters have no sense of humor is because humor is an interrupted defense mechanism?
Usually, it has to involve an impact of some sort to the nads.
Humour usually depends upon some unexpected surprise, paradox or other logical “short circuit” triggering the laugh response in the limbic system.
*Hey, what’s so funny?
Sorry dude, you’re just modulating my mesolimbic reward centres.*
It works like this.
I saw Harold and Kumar Go To White Castle and in the scene where they are in jail with the phlegmatic black guy as they escape he is being assaulted in the background. You hear one of the guards say “Look out he’s got a gun” and the black guy resignedly says “It’s a book”…thump…thump
weeks later I was reading a book while my son was watching something on TV and someone said “Look out he’s got a gun.” and I burst out laughing.
There are some elements that a great number of jokes have in common - surprise is a big one - but I don’t think there’s one category for all jokes, or one characteristic all jokes have in common.
A few different groups of researchers in recent years have tried to find “the world’s funniest joke.” What they always ended up finding were simple and inoffensive jokes that a large number of people would get and might find mildly funny, but that nobody in his right mind would call the funniest joke ever told. People don’t laugh at jokes they’re told all that much. Things that happen to you (or someone you’re with) are much funnier. So I’m going to say no. So many funny things are events or incongruities and not statements at all - things that without context are worthless - that I don’t think a computer could do it. And then there’s the subjective nature of humor, already mentioned.
Oh, OK, got it. 
Now if only I could explain to the aliens why I’m laughing at the abstruseness of that abstract.
No, no, no, you’re getting it ALL wrong.
The aliens came UP with humor in the first place!! They’re using it to experiment on us and understand our psychology. It’s only human beings who don’t understand why something is funny…
(Credits to Isaac Asimov, that dearly departed ‘Jokester’)